1. Field of the Invention
The present invention relates to a closure system, a method of use of same, and devices including the closure system such as, by way of example, a chest roller, a snatch block, and an ascender.
2. State of the Art
Chest rollers are used for various applications in many different activities. A conventional chest roller 10, depicted in FIG. 1 is typically associated with rope work in vertical terrain, such as caving and rescue work. An individual ascending or descending a free-hanging rope may be secured to the rope with a waist harness, and a chest roller is worn to keep the individual in an upright position, with his or her chest proximate the rope. A baseplate 11 may be affixed to the chest of the individual as by straps or webbing, and the rope will pass through opening 16 and abut sheave 12. As the individual ascends or descends, the chest roller 10 also moves up or down on the rope, and the sheave 12 rotates about an axle or pin (unnumbered) affixed to a pedestal 13 to minimize the friction on the rope. The closure system of the chest roller 10 includes a sideplate 15 which is movable when button 14 is depressed, enabling the rope to be laterally inserted or removed from the opening 16. However, the sideplate 15 is not directly affixed to the baseplate 11, requiring any outward forces on the sheave 12 to be transferred to the baseplate 11 through pedestal 13. The uneven loading on the pedestal 13 by the cantilevered sheave 12 puts additional stress in the form of bending and shear stress on the connection between the baseplate 11 and the pedestal 13.
Carabiners are also conventionally used in roped activities. FIGS. 2A, 2B and 2C illustrate one conventional carabiner 100 in which the carabiner body 60 of the carabiner 100 consists of a single round metal shank formed in a generally C-shape with two ends, a securing end 25 and a receiving end 20. The oblong C-shape of the carabiner body 60 forms a mouth 29 between ends 20 and 25. As further shown in FIG. 2B, a gate 50 is typically a single piece made of heavy round metal wire, having two ends 74, 76. The gate wire is bent to form an oblong shape having a closed U-shaped head 58, a long arm 54 and a short arm 56 which converge upwardly. The ends 74, 76 of the gate 50 are each turned inward at a right angle about a radius to form stems 84, 86, respectively. One of arms 54, 56 is raised with respect to the other arm by being pivoted or twisted at the point connecting the arm to head 58. Accordingly, if gate 50 is placed on a level surface, the head 58 and one arm 54, 56 will lay flat, while the other arm will form an upward angle with the surface. This result will occur regardless of which arm 54, 56 is placed on the level surface.
The securing end 25 of the carabiner 100 is slightly tapered to form flattened, parallel side surfaces, and two linearly adjacent supporting holes 24, 26 are bored therethrough. The diameter of the wire for the gate 50 is substantially smaller than the diameter of the carabiner body 60 so that stems 84, 86 of gate 50 fit into the supporting holes 24, 26, respectively. The stems 84, 86 are of sufficient length to pass into the entire length of supporting holes 24, 26 transverse to the side surfaces, respectively, without extending outside the respective supporting holes 24, 26. Supporting holes 24, 26 pivotally connect the gate 50 with the carabiner body 60 50 that gate 50 may be opened and closed.
In the closed position of FIG. 2A, the gate 50 extends to the receiving end 20 of the carabiner body 60. Since one arm 54, 56 of gate 50 is twisted and supporting holes 24, 26 are linearly aligned, a spring-like, biasing force is created when gate 50 is connected to the securing end 25. Accordingly, head 58 of gate 50 is biased to the closed position against the inside of the receiving end 20 of the carabiner body 60. The gate 50 may thus provide structural support for the carabiner 100 under tensile loading along the major axis 55. As shown in FIG. 2c gate 50 may be opened by applying an inward force on the gate 50. The gate 50 of the carabiner 100 provides a closure system with structural support; however, the gate 50 is prone to an accidental opening because only an inward force in a single direction is required to cause the gate 50 to open.
In view of the foregoing, it appears that a closure system having a quick and straightforward sideplate opening and closing mechanism that may be securely closed is needed. A sideplate configuration adding structural support would also be useful.